232 " ENDEAVOUK " SCIENTIFIC RESULTS. 



minute interjjolated denticles between the ordinary teeth 

 seem to occur only very rarely. True Umbrella wanting ; 

 tentacle sheath only weakly developed. 



In the d^ both arms of the ventral pair conspicuously modi- 

 fied (PI. Ixiv. ; PI. Ixv., figs. 2-6 ; PI. Ixvi., figs. 3-6), perhaps 

 as clasping organs. Right ventral arm, which is the true 

 Hectocotyliis, conspicuously differentiated into three main 

 divisions — a heavily tuberculate basal region, a narrowed 

 median sucker-bearing region, and a curiously pectinated 

 distal portion which first expands, then tapers rapidly to an 

 atteniiate point. Taking a concrete instance to avoid the 

 confusion which might ensue from the great variation in the 

 deta.ils of these organs — in one of the larger examples before 

 me [549] the right ventral arm has the suckers of the five 

 proximal pairs missing (PI. Ixv., fig. 2), their original position 

 evident from their immensely enlarged basal cushions, espe- 

 cially those of the ventral series which are vertical, acutely 

 pointed, angular, and sharply carinated on the inner side, but 

 with their outer faces deeply excavated (PI. Ixv., fig. 6), so 

 that they much resemble the prows of small canoes stuck 

 on end, although the proximal ridge on the outer side of each 

 is not quite confluent toward the tip with the more distal 

 ridge ; on the proximal face near the point occurs a small 

 elongate tubercle marking the original point of attachment 

 of the sucker pedicel (PI. Ixv., fig. 2) ; corresponding cushions 

 of dorsal row only a little more than one-half the height of the 

 ventral cushions and more uniform in size, the former sucker 

 bases on the other hand better developed'so that the cushions 

 are given a four-sided shape, all the ridges being verj'^ sharp ; 

 in the dorsal row the cushions gradually increase in size to 

 the second or third, thence diminishing again, in the ventral 

 row to the third or fourth, the difference in the size of the 

 cushions being likewise more marked ; sixth cushion in each 

 series considerably smaller than those preceding it and 

 bearing a small sucker. Next five pairs of suckers, except 

 for their thickened, outwardly bifurcating bases and small 

 size, relatively normal in their similarity to suckers corre- 

 spondingly situated on the three dorsal pairs of arms ; sucker- 

 bearing face of arm here much narrowed, the lower portions 

 of the basal cushions connected by a stout, upstanding, 

 marginal web, abruptly terminating dorsally with the last 

 of the sucker-bearing cushions (sucker missing from this 

 cushion in the present specimen), but continuous ventrally to 

 the tip of the arm (PI. Ixv., figs. 2, 4) ; remainder of arm of 

 very different structure and, except for two suckers persisting 



